Due to the fundamental role apoptosis plays in developmental processes, cell death mechanisms in eukaryotes have been the focus of intense research. However, the realization that prokaryotes also posses highly regulated cell death mechanisms is relatively new; consequently, little research has been done in this area. The prokaryotic soil bacterium, Myxococcus xanthus is a well developed model system that exhibits a form of regulated cell death during ifruiting body formation. In our preliminary studies we found a novel protein, Bapl (bacterial apoptosis protein 1), that modulates cell death during development and which has significant homology to the human caspase activator, Apaf-1 (apoptotic protease activating factor 1). In this study, we seek to gather additional evidence in support of the idea that an evolutionary link exists between the standard model of eukaryotic apoptosis and the highly regulated form of cell death observed in M. xanthus. We intend to establish this connection at the molecular level through the investigation of the apoptotic pathway. To accomplish this goal, we propose three study aims: 1) the identification of novel Bapl interacting proteins through yeast two hybrid studies 2) the discovery of new loci using DNA microarrays and 3) the functional characterization of these gene candidates through detailed gene inactivation studies.